Multiple beam generation from a single source beam for use with a lidar system

ABSTRACT

Embodiments discussed herein refer to generating multiple laser beams from a single beam source. Single source multi-beam splitters can produce multiple beams from a single source, precisely control the exit angle of each beam, and ensure that each beam has substantially the same intensity.

This application is a continuation application of U.S. patentapplication Ser. No. 16/777,059, filed on Jan. 30, 2020, which claimsthe benefit of U.S. Provisional Application No. 62/803,788, filed Feb.11, 2019. The contents of both applications are incorporated herein intheir entireties for all purposes.

FIELD OF THE INVENTION

The present disclosure relates generally to laser scanning and, moreparticularly, to using a generating multiple laser beams from a singlebeam source.

BACKGROUND

Systems exist that enable vehicles to be driven semi-autonomously orfully autonomously. Such systems may use one or more range finding,mapping, or object detection systems to provide sensory input to assistin semi-autonomous or fully autonomous vehicle control. Light detectionand ranging (LiDAR) systems, for example, can provide the sensory inputrequired by a semi-autonomous or fully autonomous vehicle. LiDAR systemsuse light pulses to create an image or point cloud of the externalenvironment. Some typical LiDAR systems include a light source, a pulsesteering system, and light detector. The light source generates lightpulses that are directed by the pulse steering system in particulardirections when being transmitted from the LiDAR system. When atransmitted light pulse is scattered by an object, some of the scatteredlight is returned to the LiDAR system as a returned pulse. The lightdetector detects the returned pulse. Using the time it took for thereturned pulse to be detected after the light pulse was transmitted andthe speed of light, the LiDAR system can determine the distance to theobject along the path of the transmitted light pulse. The pulse steeringsystem can direct light pulses along different paths to allow the LiDARsystem to scan the surrounding environment and produce an image or pointcloud. LiDAR systems can also use techniques other than time-of-flightand scanning to measure the surrounding environment

BRIEF SUMMARY

Embodiments discussed herein refer to generating multiple laser beamsfrom a single beam source by using a single source, multi-beam (SSMB)splitter. SSMB splitters according to embodiments discussed herein canproduce multiple beams from a single source, precisely control the exitangle of each beam, and ensure that each beam has substantially the sameintensity.

In one embodiment, a wedge splitter for use with a light detection andranging (LiDAR) system is provided that includes a prism structure thatincludes a beam injection portion for receiving a light beam at an angleof incidence (AOI); a first planar surface arranged at a first relativeangle; and a second planar surface arrange at a second relative anglethat differs from the first relative angle by a wedge angle. The wedgesplitter includes a plurality of beam intensity equalizing portionsdisposed on the prism structure, wherein the prism structure emits aplurality of output beams that are derived from the received light beamvia the plurality of beam intensity equalizing portions, wherein the AOIand the wedge angle control an output angle of each of the pluralityoutput beams such that each of the plurality output beams converge at acommon point in space a fixed distance away from the wedge splitter, andwherein each of the plurality of beam intensity equalizing portionscontrol a respective reflectivity/transmissivity ratio to ensure thateach of the plurality output beams has a substantially similarintensity.

In one embodiment, the output angle of each of the plurality outputbeams is such that an inter-beam angle between adjacent output beams ofthe plurality of output beams is the same.

In one embodiment, the inter-beam angle is 1.12 degrees.

In one embodiment, the plurality output beams comprises four outputbeams.

In one embodiment, the prism structure is a trapezoidal prism.

In one embodiment, the second planar surface comprises a mirror coating.

In one embodiment, each of the plurality of beam intensity equalizingportions comprises a dielectric layer or a metal layer.

In one embodiment, the wedge angle ranges between 0.3 degrees and 0.7degrees.

In one embodiment, the first and second planar surfaces are notparallel.

In one embodiment, a single source multiple beam (SSMB) splitterincludes a monolithic structure operative to receive a single input beamand output a plurality of output beams by controlling an internalreflection path of the single input beam and output angles for each ofthe output beams such that the output beams have substantially the samebeam intensity and convergence point.

In one embodiment, the monolithic structure includes first and secondplanar surfaces that differ in respective relative angles by a wedgeangle that is, at least in part, responsible for controlling theinternal reflection path and exit angles of each of the output beams.

In one embodiment, the monolithic structure includes a plurality ofdiscreet beam intensity equalizing portions that control the beamintensity of the plurality of output beams.

In one embodiment, the monolithic structure includes a continuouslyvariable beam intensity equalizing layer that controls the beamintensity of the plurality of output beams.

In one embodiment, the output angle of each of the plurality outputbeams is such that an inter-beam angle between adjacent output beams isthe same.

In one embodiment, the monolithic structure is a trapezoidal prism.

In one embodiment, a single source multiple beam (SSMB) splitterincludes a stacked splitter array configured to receive a light beam,the stacked splitter array comprising a plurality of prism structuresthat provide a plurality of interstitial light beams based on thereceived light beam, wherein the plurality of interstitial light beamsare redirected at the same interstitial beam angle and beam intensity,and a faceted deflector that provides a plurality of output beams basedon the interstitial light beams by redirecting each of the plurality ofinterstitial light beams along respective output angles.

In one embodiment, the plurality of output beams are substantially equalin intensity and converge at the same point a fixed distance away fromthe SSMB splitter.

In one embodiment, the SSMB splitter further includes a divergence lensthat partially diverges the light beam before it is received by thestacked splitter array.

In one embodiment, the faceted deflector includes a planoconvex lens.

In one embodiment, a LiDAR system is provided that includes a beamsteering system, which includes a polygon structure, and a mirrorcoupled to a mirror controller that controls movement speed anddirection of the mirror. The LiDAR system includes a laser subsystemincluding a laser source and a single source multiple beam (SSMB)splitter that produces a plurality of output beams that are steered bythe beam steering system in accordance with a field of view (FOV), and aregion of interest (ROI) controller coupled to the beam steering systemand the laser subsystem, the ROI controller operative to coordinate themovement speed of the mirror and light pulse intervals when the lightpulses emitted by the laser system are steered to at least one ROIwithin the FOV.

In one embodiment, the plurality of output beams are substantially equalin intensity and have the same inter-beam angle.

In one embodiment, the ROI controller is operative to control the mirrormovement speed based on the inter-beam angle, a frame rate in which thebeam steering system scans the FOV, and the at least one ROI.

In one embodiment, the ROI controller is operative to control the mirrormovement speed based on a desired angular resolution.

In one embodiment, the SSMB splitter comprises a monolithic structureoperative to receive a single input beam and output the plurality ofoutput beams by controlling an internal reflection path of the singleinput beam and output angles for each of the output beams such that theoutput beams have substantially the same beam intensity and convergencepoint

In one embodiment, the ROI controller is operative to, for light pulsessteered towards the at least one ROI, control the movement speed of themirror such that it is slower compared to the movement speed of themirror when the light pulses are steered towards a non-ROI.

In one embodiment, the ROI controller is operative to adjust themovement speed of the mirror based on a beam steering angle within theFOV.

In one embodiment, the ROI controller is operative to adjust arepetition rate of the light pulses based on the beam steering angle.

A further understanding of the nature and advantages of the embodimentsdiscussed herein may be realized by reference to the remaining portionsof the specification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2, and 3 illustrate an exemplary LiDAR system using pulsesignal to measure distances to points in the outside environment.

FIG. 4 depicts a logical block diagram of the exemplary LiDAR system.

FIG. 5 depicts a light source of the exemplary LiDAR system.

FIG. 6 depicts a light detector of the exemplary LiDAR system.

FIG. 7 depicts an embodiment of a signal steering system using a singlelight source and detector.

FIG. 8 depicts an embodiment of a signal steering system using two lightsources and two detectors.

FIG. 9 depicts a portion of the scan pattern generated by the embodimentfrom FIG. 8 .

FIG. 10 depicts a portion of the scan pattern according to anotherembodiment.

FIG. 11 depicts a portion of the scan pattern according to yet anotherembodiment.

FIG. 12 shows illustrative field of view of a LiDAR system according toan embodiment.

FIGS. 13A and 13B show illustrative block diagrams of LiDAR systemsaccording to various embodiments.

FIG. 14 shows an illustrative fiber tip arrangement according to anembodiment.

FIGS. 15A and 15B show multiple mirror alignment arrangement that may beused for ROI and non-ROI embodiments.

FIG. 15C shows an illustrative multiple collimator arrangement that maybe used for ROI and non-ROI embodiments.

FIG. 15D shows an illustrative collimator and lens arrangement accordingto an embodiment.

FIG. 16 shows illustrative scanning resolution using multiple fibertips, a multiple mirror alignment arrangement, or multiple collimatorarrangement according to an embodiment.

FIG. 17A shows another illustrative diagram of vertical resolution usingmultiple fiber tips or a multiple mirror alignment arrangement,according to an embodiment.

FIG. 17B shows an illustrative close-up view of a sparse region withinFIG. 17A and

FIG. 17C shows an illustrative close-up view of the dense region withinFIG. 17A, according to various embodiments.

FIG. 18 shows illustrative an FOV with variable sized laser pulsesaccording to an embodiment.

FIG. 19 shows illustrative splitter according to an embodiment.

FIG. 20 shows an illustrative block diagram of a splitter according toan embodiment.

FIGS. 21A, 21B, and 21C show illustrative wedge splitters according tovarious embodiment.

FIGS. 22A and 22B show illustrative side and perspective views of awedge splitter according to an embodiment.

FIGS. 22C and 22D show illustrative perspective and side views of awedge splitter according to an embodiment.

FIGS. 22E and 22F show illustrative perspective views of a wedgesplitter according to an embodiment.

FIG. 22G show an alternative version of the wedge splitter of FIG. 22Faccording to an embodiment.

FIGS. 23, 24, and 25 show illustrative wedge splitter according tovarious embodiments.

FIG. 26A shows illustrative splitter according to an embodiment.

FIG. 26B shows illustrative faceted deflector according to anembodiment.

FIG. 27A shows illustrative splitter according to an embodiment.

FIG. 27B shows illustrative faceted deflector according to anembodiment.

DETAILED DESCRIPTION

Illustrative embodiments are now described more fully hereinafter withreference to the accompanying drawings, in which representative examplesare shown. Indeed, the disclosed LiDAR systems and methods may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Like numbers refer to like elementsthroughout.

In the following detailed description, for purposes of explanation,numerous specific details are set forth to provide a thoroughunderstanding of the various embodiments. Those of ordinary skill in theart will realize that these various embodiments are illustrative onlyand are not intended to be limiting in any way. Other embodiments willreadily suggest themselves to such skilled persons having the benefit ofthis disclosure.

In addition, for clarity purposes, not all of the routine features ofthe embodiments described herein are shown or described. One of ordinaryskill in the art would readily appreciate that in the development of anysuch actual embodiment, numerous embodiment-specific decisions may berequired to achieve specific design objectives. These design objectiveswill vary from one embodiment to another and from one developer toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would nevertheless be a routineengineering undertaking for those of ordinary skill in the art havingthe benefit of this disclosure.

Some light detection and ranging (LiDAR) systems use a single lightsource to produce one or more light signals of a single wavelength thatscan the surrounding environment. The signals are scanned using steeringsystems that direct the pulses in one or two dimensions to cover an areaof the surrounding environment (the scan area). When these systems usemechanical means to direct the pulses, the system complexity increasesbecause more moving parts are required. Additionally, only a singlesignal can be emitted at any one time because two or more identicalsignals would introduce ambiguity in returned signals. In someembodiments of the present technology, these disadvantages and/or othersare overcome.

For example, some embodiments of the present technology use one or morelight sources that produce light signals of different wavelengths and/oralong different optical paths. These light sources provide the signalsto a signal steering system at different angles so that the scan areasfor the light signals are different (e.g., if two light sources are usedto create two light signals, the scan area associated with each lightsource is different). This allows for tuning the signals to appropriatetransmit powers and the possibility of having overlapping scan areasthat cover scans of different distances. Longer ranges can be scannedwith signals having higher power and/or slower repetition rate (e.g.,when using pulsed light signals). Shorter ranges can be scanned withsignals having lower power and/or high repetition rate (e.g., when usingpulse light signals) to increase point density.

As another example, some embodiments of the present technology usesignal steering systems with one or more dispersion elements (e.g.,gratings, optical combs, prisms, etc.) to direct pulse signals based onthe wavelength of the pulse. A dispersion element can make fineadjustments to a pulse's optical path, which may be difficult orimpossible with mechanical systems. Additionally, using one or moredispersion elements allows the signal steering system to use fewmechanical components to achieve the desired scanning capabilities. Thisresults in a simpler, more efficient (e.g., lower power) design that ispotentially more reliable (due to few moving components).

Some LiDAR systems use the time-of-flight of light signals (e.g., lightpulses) to determine the distance to objects in the path of the light.For example, with respect to FIG. 1 , an exemplary LiDAR system 100includes a laser light source (e.g., a fiber laser), a steering system(e.g., a system of one or more moving mirrors), and a light detector(e.g., a photon detector with one or more optics). LiDAR system 100transmits light pulse 102 along path 104 as determined by the steeringsystem of LiDAR system 100. In the depicted example, light pulse 102,which is generated by the laser light source, is a short pulse of laserlight. Further, the signal steering system of the LiDAR system 100 is apulse signal steering system. However, it should be appreciated thatLiDAR systems can operate by generating, transmitting, and detectinglight signals that are not pulsed can be used to derive ranges to objectin the surrounding environment using techniques other thantime-of-flight. For example, some LiDAR systems use frequency modulatedcontinuous waves (i.e., “FMCW”). It should be further appreciated thatany of the techniques described herein with respect to time-of-flightbased systems that use pulses also may be applicable to LiDAR systemsthat do not use one or both of these techniques.

Referring back to FIG. 1 (a time-of-flight LiDAR system that uses lightpulses) when light pulse 102 reaches object 106, light pulse 102scatters and returned light pulse 108 will be reflected back to system100 along path 110. The time from when transmitted light pulse 102leaves LiDAR system 100 to when returned light pulse 108 arrives back atLiDAR system 100 can be measured (e.g., by a processor or otherelectronics within the LiDAR system). This time-of-flight combined withthe knowledge of the speed of light can be used to determine therange/distance from LiDAR system 100 to the point on object 106 wherelight pulse 102 scattered.

By directing many light pulses, as depicted in FIG. 2 , LiDAR system 100scans the external environment (e.g., by directing light pulses 102,202, 206, 210 along paths 104, 204, 208, 212, respectively). As depictedin FIG. 3 , LiDAR system 100 receives returned light pulses 108, 302,306 (which correspond to transmitted light pulses 102, 202, 210,respectively) back after objects 106 and 214 scatter the transmittedlight pulses and reflect pulses back along paths 110, 304, 308,respectively. Based on the direction of the transmitted light pulses (asdetermined by LiDAR system 100) as well as the calculated range fromLiDAR system 100 to the points on objects that scatter the light pulses(e.g., the points on objects 106 and 214), the surroundings within thedetection range (e.g., the field of view between path 104 and 212,inclusively) can be precisely plotted (e.g., a point cloud or image canbe created).

If a corresponding light pulse is not received for a particulartransmitted light pulse, then it can be determined that there are noobjects that can scatter sufficient amount of signal for the LiDAR lightpulse within a certain range of LiDAR system 100 (e.g., the max scanningdistance of LiDAR system 100). For example, in FIG. 2 , light pulse 206will not have a corresponding returned light pulse (as depicted in FIG.3 ) because it did not produce a scattering event along its transmissionpath 208 within the predetermined detection range. LiDAR system 100 (oran external system communication with LiDAR system 100) can interpretthis as no object being along path 208 within the detection range ofLiDAR system 100.

In FIG. 2 , transmitted light pulses 102, 202, 206, 210 can betransmitted in any order, serially, in parallel, or based on othertimings with respect to each other. Additionally, while FIG. 2 depicts a1-dimensional array of transmitted light pulses, LiDAR system 100optionally also directs similar arrays of transmitted light pulses alongother planes so that a 2-dimensional array of light pulses istransmitted. This 2-dimensional array can be transmitted point-by-point,line-by-line, all at once, or in some other manner. The point cloud orimage from a 1-dimensional array (e.g., a single horizontal line) willproduce 2-dimensional information (e.g., (1) the horizontal transmissiondirection and (2) the range to objects). The point cloud or image from a2-dimensional array will have 3-dimensional information (e.g., (1) thehorizontal transmission direction, (2) the vertical transmissiondirection, and (3) the range to objects).

The density of points in point cloud or image from a LiDAR system 100 isequal to the number of pulses divided by the field of view. Given thatthe field of view is fixed, to increase the density of points generatedby one set of transmission-receiving optics, the LiDAR system shouldfire a pulse more frequently, in other words, a light source with ahigher repetition rate is needed. However, by sending pulses morefrequently the farthest distance that the LiDAR system can detect may bemore limited. For example, if a returned signal from a far object isreceived after the system transmits the next pulse, the return signalsmay be detected in a different order than the order in which thecorresponding signals are transmitted and get mixed up if the systemcannot correctly correlate the returned signals with the transmittedsignals. To illustrate, consider an exemplary LiDAR system that cantransmit laser pulses with a repetition rate between 500 kHz and 1 MHz.Based on the time it takes for a pulse to return to the LiDAR system andto avoid mix-up of returned pulses from consecutive pulses inconventional LiDAR design, the farthest distance the LiDAR system candetect may be 300 meters and 150 meters for 500 kHz and 1 Mhz,respectively. The density of points of a LiDAR system with 500 kHzrepetition rate is half of that with 1 MHz. Thus, this exampledemonstrates that, if the system cannot correctly correlate returnedsignals that arrive out of order, increasing the repetition rate from500 kHz to 1 Mhz (and thus improving the density of points of thesystem) would significantly reduce the detection range of the system.

FIG. 4 depicts a logical block diagram of LiDAR system 100, whichincludes light source 402, signal steering system 404, pulse detector406, and controller 408. These components are coupled together usingcommunications paths 410, 412, 414, 416, and 418. These communicationspaths represent communication (bidirectional or unidirectional) amongthe various LiDAR system components but need not be physical componentsthemselves. While the communications paths can be implemented by one ormore electrical wires, busses, or optical fibers, the communicationpaths can also be wireless channels or open-air optical paths so that nophysical communication medium is present. For example, in one exemplaryLiDAR system, communication path 410 is one or more optical fibers,communication path 412 represents an optical path, and communicationpaths 414, 416, 418, and 420 are all one or more electrical wires thatcarry electrical signals. The communications paths can also include morethan one of the above types of communication mediums (e.g., they caninclude an optical fiber and an optical path or one or more opticalfibers and one or more electrical wires).

LiDAR system 100 can also include other components not depicted in FIG.4 , such as power buses, power supplies, LED indicators, switches, etc.Additionally, other connections among components may be present, such asa direct connection between light source 402 and light detector 406 sothat light detector 406 can accurately measure the time from when lightsource 402 transmits a light pulse until light detector 406 detects areturned light pulse.

FIG. 5 depicts a logical block diagram of one example of light source402 that is based on a fiber laser, although any number of light sourceswith varying architecture could be used as part of the LiDAR system.Light source 402 uses seed 502 to generate initial light pulses of oneor more wavelengths (e.g., 1550 nm), which are provided towavelength-division multiplexor (WDM) 504 via fiber 503. Pump 506 alsoprovides laser power (of a different wavelength, such as 980 nm) to WDM504 via fiber 505. The output of WDM 504 is provided to pre-amplifiers508 (which includes one or more amplifiers) which provides its output tocombiner 510 via fiber 509. Combiner 510 also takes laser power frompump 512 via fiber 511 and provides pulses via fiber 513 to boosteramplifier 514, which produces output light pulses on fiber 410. Theoutputted light pulses are then fed to steering system 404. In somevariations, light source 402 can produce pulses of different amplitudesbased on the fiber gain profile of the fiber used in the source.Communication path 416 couples light source 402 to controller 408 (FIG.4 ) so that components of light source 402 can be controlled by orotherwise communicate with controller 408. Alternatively, light source402 may include its own controller. Instead of controller 408communicating directly with components of light source 402, a dedicatedlight source controller communicates with controller 408 and controlsand/or communicates with the components of light source 402. Lightsource 402 also includes other components not shown, such as one or morepower connectors, power supplies, and/or power lines.

Some other light sources include one or more laser diodes, short-cavityfiber lasers, solid-state lasers, and/or tunable external cavity diodelasers, configured to generate one or more light signals at variouswavelengths. In some examples, light sources use amplifiers (e.g.,pre-amps or booster amps) include a doped optical fiber amplifier, asolid-state bulk amplifier, and/or a semiconductor optical amplifier,configured to receive and amplify light signals.

Returning to FIG. 4 , signal steering system 404 includes any number ofcomponents for steering light signals generated by light source 402. Insome examples, signal steering system 404 may include one or moreoptical redirection elements (e.g., mirrors or lens) that steer lightpulses (e.g., by rotating, vibrating, or directing) along a transmitpath to scan the external environment. For example, these opticalredirection elements may include MEMS mirrors, rotating polyhedronmirrors, or stationary mirrors to steer the transmitted pulse signals todifferent directions. Signal steering system 404 optionally alsoincludes other optical components, such as dispersion optics (e.g.,diffuser lenses, prisms, or gratings) to further expand the coverage ofthe transmitted signal in order to increase the LiDAR system 100'stransmission area (i.e., field of view). An example signal steeringsystem is described in U.S. patent application Ser. No. 15/721,127 filedon Sep. 29, 2017, entitled “2D Scanning High Precision LiDAR UsingCombination of Rotating Concave Mirror and Beam Steering Devices,” thecontent of which is incorporated by reference in its entirety herein forall purposes. In some examples, signal steering system 404 does notcontain any active optical components (e.g., it does not contain anyamplifiers). In some other examples, one or more of the components fromlight source 402, such as a booster amplifier, may be included in signalsteering system 404. In some instances, signal steering system 404 canbe considered a LiDAR head or LiDAR scanner.

Some implementations of signal steering systems include one or moreoptical redirection elements (e.g., mirrors or lens) that steersreturned light signals (e.g., by rotating, vibrating, or directing)along a receive path to direct the returned light signals to the lightdetector. The optical redirection elements that direct light signalsalong the transmit and receive paths may be the same components (e.g.,shared), separate components (e.g., dedicated), and/or a combination ofshared and separate components. This means that in some cases thetransmit and receive paths are different although they may partiallyoverlap (or in some cases, substantially overlap).

FIG. 6 depicts a logical block diagram of one possible arrangement ofcomponents in light detector 404 of LiDAR system 100 (FIG. 4 ). Lightdetector 404 includes optics 604 (e.g., a system of one or more opticallenses) and detector 602 (e.g., a charge coupled device (CCD), aphotodiode, an avalanche photodiode, a photomultiplier vacuum tube, animage sensor, etc.) that is connected to controller 408 (FIG. 4 ) viacommunication path 418. The optics 604 may include one or more photolenses to receive, focus, and direct the returned signals. Lightdetector 404 can include filters to selectively pass light of certainwavelengths. Light detector 404 can also include a timing circuit thatmeasures the time from when a pulse is transmitted to when acorresponding returned pulse is detected. This data can then betransmitted to controller 408 (FIG. 4 ) or to other devices viacommunication line 418. Light detector 404 can also receive informationabout when light source 402 transmitted a light pulse via communicationline 418 or other communications lines that are not shown (e.g., anoptical fiber from light source 402 that samples transmitted lightpulses). Alternatively, light detector 404 can provide signals viacommunication line 418 that indicate when returned light pulses aredetected. Other pulse data, such as power, pulse shape, and/orwavelength, can also be communicated.

Returning to FIG. 4 , controller 408 contains components for the controlof LiDAR system 100 and communication with external devices that use thesystem. For example, controller 408 optionally includes one or moreprocessors, memories, communication interfaces, sensors, storagedevices, clocks, ASICs, FPGAs, and/or other devices that control lightsource 402, signal steering system 404, and/or light detector 406. Insome examples, controller 408 controls the power, rate, timing, and/orother properties of light signals generated by light source 402;controls the speed, transmit direction, and/or other parameters of lightsteering system 404; and/or controls the sensitivity and/or otherparameters of light detector 406.

Controller 408 optionally is also configured to process data receivedfrom these components. In some examples, controller determines the timeit takes from transmitting a light pulse until a corresponding returnedlight pulse is received; determines when a returned light pulse is notreceived for a transmitted light pulse; determines the transmitteddirection (e.g., horizontal and/or vertical information) for atransmitted/returned light pulse; determines the estimated range in aparticular direction; and/or determines any other type of data relevantto LiDAR system 100.

FIG. 7 depicts an embodiment of a signal steering system (e.g., signalsteering system 404 of FIG. 4 ) according to some embodiments of thepresent technology. Polygon 702 has ten reflective sides (sides702A-702E are visible in FIG. 7 ) but can have any number of reflectivesides. For example, other examples of polygon 702 has 6, 8, or 20 sides.Polygon 702 rotates about axis 703 based on a drive motor (not shown) toscan signals delivered from a light source (e.g., via output 706, whichis connected to a light source such as light source 402 described above)along a direction perpendicular or at a non-zero angle to axis ofrotation 703.

Mirror galvanometer 704 is positioned next to polygon 702 so that one ormore signals emitted from light source output 706 (e.g., a fiber tip)reflect off of mirror galvanometer 704 and onto rotating polygon 702.Mirror galvanometer 704 can sometimes be referred to as a galvo. Mirrorgalvanometer 704 tilts so as to scan one or more signals from output 706to a direction different than the direction that polygon 702 scanssignals (e.g., edges 704A and 704B tilt towards and away from polygon702 about axis so as to scan pulses along a path that is parallel or atan angle to the axis of rotation of polygon 702). In some examples,polygon 702 is responsible for scanning one or more signals in thehorizontal direction of the LiDAR system and mirror galvanometer 704 isresponsible for scanning one or more signals in the vertical direction.In some other examples, polygon 702 and mirror galvanometer 704 areconfigured in the reverse manner. While the example in FIG. 7 uses amirror galvanometer, other components can be used in its place. Forexample, one or more rotating mirrors or a grating (with differentwavelength pulses) may be used. The solid black line represents oneexample signal path through the signal steering system.

Light returned from signal scattering (e.g., when a light hits anobject) within region 708 (indicated by dashed lines) is returned torotating polygon 702, reflected back to mirror galvanometer 704, andfocused by lens 710 onto detector 712. While lens 710 is depicted as asingle lens, in some variations it is a system of one or more optics.

FIG. 8 depicts a similar system as depicted in FIG. 7 except a secondlight source is added that provides one or more signals from output 714.The light source for output 714 may be the same or different than thelight source for output 706, and the light transmitted by output 714 mayhave the same or a different wavelength as the light transmitted byoutput 706. Using multiple light outputs can increase the points densityof a points map without sacrificing the maximum unambiguous detectionrange of the system. For example, light output 714 can be positioned totransmit light at a different angle from output 706. Because of thedifferent angles, light transmitted from light source 706 is directed toan area different from light transmitted from output 714. The dottedline shows one example pulse path for pulses emitted from output 714.Consequently, one or more objects located at two different areas withina region can scatter and return light to the LiDAR system. For example,the region 716 (the dashed/double-dotted line) indicates the region fromwhich return signals from scattered signals returns to the LiDAR system.The returned light is reflected off polygon 702 and mirror galvanometer704 and focused on detectors 712 and 718 by lens 710. Detectors 712 and718 can each be configured to receive returned light from one of theoutputs 706 and 714, and such configuration can be achieved by preciselycontrolling the position of the detectors 712 and 718 as well as thewavelength(s) of the transmitted light. Note that the same lens (oroptic system) can be used for both detector 712 and 718. The offsetbetween outputs 706 and 714 means that the light returned to the LiDARsystem will have a similar offset. By properly positioning detectors 712and 718 based on the relative positioning of their respective lightsource outputs (e.g., respective positions of outputs 706 and 714) and,optionally, by properly controlling the wavelength(s) of the transmittedlight, the returned light will be properly focused on to the correctdetectors, and each received light can be a point in the points map.Therefore, compare to the system with only one output 706, the systemwith two outputs can maintain the same pulse repetition rate and producetwice the number of points or reduce the pulse repetition rate by halfand still produce the same number of points. As a non-limiting example,a system with two light outputs can reduce the pulse repetition ratefrom 1 MHz to 500 KHz, thereby increasing its maximum unambiguousdetection range from 150 meters to 300 meters, without sacrificingpoints density of the resulting points map. A pulse repetition rate ofbetween 200 and 2 MHz is contemplated and disclosed.

FIG. 9 depicts a point map from a first design. This design has twochannels (e.g., two light source outputs and two light detectors) placedin a way that the exiting beams have an angle of 8 degrees vertically.The scanned pattern has vertical overlap. The scanned range is +−56degrees horizontally and +12˜−20 degrees vertically.

FIG. 10 depicts a point map from a second design. This design has twochannels (e.g., two light source outputs and two light detectors) placedin a way that the exiting beams have an angle of 6 degrees. The scannedpattern has horizontal overlap (+−45 degrees). The scanned range is +−67degrees horizontally and +12˜−20 degrees vertically.

Exiting beams of two channels are not necessary to separate with acertain angle (e.g. 6 degree in FIG. 10 ) to obtain a larger horizontalrange. Horizontal displacement of existing beams can be used to expandthe horizontal range. For example, two exit beams may be pointed thatsame angle, but are offset with respect to each other in the same plane.Due to these different positions, each channel is reflected by differentpart of polygon and therefore covers a different horizontal range. Bycombining the two channels, the total horizontal range is increased.

FIG. 11 depicts a point map from a third design. This design has threechannels (e.g., three light source outputs and three light detectors) toincrease point density. About 2.88 million points per second can beobtained by using 3 fiber tips and 3 detectors. The resolution can befurther reduced to 0.07 degrees for both directions. The speed of thepolygon can be reduced to 6000 rpm.

FIG. 12 shows illustrative field of view (FM) 1200 of a LiDAR systemaccording to an embodiment. As shown, FOV 1200 is a two-dimensionalspace bounded by X and Y dimensions. Although the LiDAR system cancollect data points from the entirety of FOV 1200, certain regions ofinterest (ROI) may have higher precedence over other regions within FOV1200 (e.g., such as undesired regions that occupy all space within FOV1200 that is not a ROI). FIG. 12 shows five different illustrative ROIs1210-1214 to illustrate different regions within FOV 1200 that requireadditional data points than other regions within FOV 1200. For example,ROI 1210 occupies an entire band of a fixed y-axis height across thex-axis of FOV 1200. ROIs 1211 and 1212 show localized ROIs below ROI1210, and ROIs 1213 and 1214 show localized ROIs above ROI 1210. Itshould be understood that any number of ROIs may exist and that the ROIscan occupy any portion of FOV 1200. Embodiments discussed herein enableadditional data points to be collected in the ROIs in a manner that doesnot disrupt the operation of the LiDAR system.

FIG. 13A shows an illustrative block diagram of LiDAR system 1300according to an embodiment. LiDAR system 1300 can include lasersubsystem 1310, receiver system 1320, laser controller 1330, region ofinterest controller 1340, polygon structure 1350, polygon controller1355, mirror 1360, and mirror controller 1365. LiDAR system 1300 may becontained within one or more housings. In multiple housing embodiments,at least one of the housings may be a temperature controlled environmentin which selection portions of LiDAR system 1300 (e.g., laser controller1330, laser source 1312, controller 1340) are contained therein.

Laser subsystem 1310 may be operative to direct light energy towardsmirror 1360, which redirects the light energy to polygon structure 1350.Mirror 1360 also operative to redirect light enemy received from polygonstructure 1350 to receiver system 220. Mirror 1360 may be moved underthe control of mirror controller 1365, which can control the speed anddirection of mirror movement. As mirror 1360 moves, it causes lightbeing transmitted by laser subsystem 1310 to interface with differentportions of polygon structure 1350. Polygon structure 1350 is movingunder the control of polygon controller 1355 and is operative to directthe light energy received from mirror 1360 in accordance with the fieldof view parameters of LiDAR system 1300. That is, if LiDAR system 1300has a field of view with range of z, a lateral angle of x, and verticalangle of y, the range z can be controlled by the power of laser source1312, the vertical angle y can be controlled by the movement of mirror1360, and the lateral angle x can be controlled by polygon structure1350. Light energy that is reflected back from objects in the field ofview and returns to polygon structure 1350 where it is directed back tomirror 1360, which redirects it back to receiver system 1320.

As defined herein, a frame rate may refer to the time it takes forscanning system 1302 to complete one full scan of the FOV. For eachframe, scanning system 1302 can obtain data points from each row (orcolumn) of a plurality of rows (or columns) that are defined by the FOV.Each row may correspond to a vertical angle within the vertical range ofthe FOV. The vertical angle is controlled by mirror 1360. As mirror 1360moves, the vertical angle changes, thereby enabling scanning system 1302to obtain data points from multiple rows within the FOV. Vertical angleresolution refers spacing between adjacent rows of data points. Anincrease in vertical angular resolution corresponds to denser spacingbetween adjacent rows, and such an increase can be achieved bydecreasing the delta of the vertical angles between adjacent verticalangles. The delta between adjacent vertical angels can be decreased byslowing down the movement of mirror 1360. That is, as mirror movementspeed slows down, the change in the vertical angle delta decreases. Adecrease in vertical angular resolution corresponds to sparser spacingbetween adjacent rows, and such a decrease can be achieved by increasingthe vertical angle delta. The delta between adjacent vertical angels canbe increased by speeding up the movement of mirror 1360. That is, asmirror movement speed speeds up, the change in the vertical angle deltaincreases.

The plurality of data points obtained within any row may depend on ahorizontal angle within the horizontal range of the FOV. The horizontalrange may be controlled by polygon 1350, and the horizontal angleresolution may be controlled by a time interval of successive laserpulses. The time interval is sometimes related to the repetition rate. Asmaller time interval can result in increased horizontal angularresolution, and a larger time interval can result in decreasedhorizontal angular resolution.

The above reference to vertical and horizontal angles and vertical andhorizontal angular resolution was made in reference to a system in whichmirror 1360 controls the vertical angle. It should be understood thatmirror 1360 can be repurposed to control the horizontal angle and usedin a system different than that shown in FIG. 13 .

Laser subsystem 1310 can include laser source 1312 and fiber tips1314-1316. Any number of fiber tips may be used as indicated the “n”designation of fiber tip 1316. As shown, each of fiber tips 1314-1316may be associated with laser source 1312. Laser source 1312 may be afiber laser or diode laser. Fiber tips 1314-1316 may be aligned in afixed orientation so that the light exiting each tip strikes mirror 1360at a particular location. The actual orientation may depend on severalfactors, including, for example, frame rate, mirror movement and speed,polygon speed, ROIs, repetition rate, etc. Additional discussion offiber tips and their characteristics in obtaining additional data pointswithin ROIs is discussed in more detail below.

Receiver system 1320 can include various components such as optics,detectors, control circuitry, and other circuitry. The optics maycontain light-transmitting optics that gather laser light returned frommirror 1360. Detectors may generate current or voltage signals whenexposed to light energy through the optics. The detectors may be, forexample, avalanche photo diodes. The outputs of the detectors can beprocessed by the control circuitry and delivered to a control system(not shown) to enable processing of return pulses.

Laser controller 1330 may be operative to control laser source 1312. Inparticular, laser controller 1330 can control power of laser source1312, can control a repetition rate or time interval of light pulsesemitted by laser source 1312 (via time interval adjustment module 1332),and can control pulse duration of laser source 1312. Time intervaladjustment module 1332 may be operative to control and/or adjust therepetition rate/time interval of the transmitter pulse of laser 1310.Time interval adjustment circuitry 1332 can vary the repetitionrate/time interval for different regions within the FOV. For example,the repetition rate may be increased for ROIs but may be decreased forareas of FOV that are not of interest. As another example, the timeinterval can be decreased for ROIs and increased for areas of FOV thatare not of interest.

Region of Interest controller 1340 may be operative to control LiDARsystem 1300 to obtain additional data points for the ROIs. That is, whenLiDAR system 1300 is scanning a ROI, ROI controller 1340 may causesystem 1300 to operate differently than when system 1300 is not scanninga ROI. ROI controller 1340 may control operation of laser controller1330, polygon controller 1355, and mirror controller 1365 to alter thequantity of data being obtained by system 1300. ROI controller 1340 mayreceive several inputs that dictate how it should control the scanningsubsystem 1302. The inputs can include, for example, frame rate 1342,sparse regions 1343, dense regions 1344, distance range, or any othersuitable input. Frame rate 1342 may specify the frequency at whichscanning subsystem 1302 completes a FOV scan. Sparse and dense regions1343 and 1344 may provide specific locations of ROIs. For example, denseregions 1344 may correspond to ROIs and sparse regions 1343 maycorrespond to regions within the FOV that are not ROIs. Fiber tip angles1345 may be used as a design constraint within which scanning sub-system1302 operates in order to optimally perform scanning.

Polygon structure 1350 may be constructed from a metal such as aluminum,plastic, or other material that can have a polished or mirrored surface.Polygon structure 1350 may be selectively masked to control the lateraldispersion of light energy being projected in accordance with the fieldof view of scanning subsystem 1302. Polygon structure 1350 can include anumber of facets to accommodate a desired horizontal field of view(FOV). The facets can be parallel or non-parallel to its symmetric axis.Polygon structure 1350 is operative to spin about an axis in a firstdirection at a substantially constant speed. The shape of polygonstructure 1350 can be trimmed (e.g., chop off the sharp corner or tip toreduce overall weight or required geometry envelope, chamfer the sharpedge to reduce air resistance) for better operational performance.

Mirror 1360 may be a single plane or multi-plane mirror that oscillatesback and forth to redirect light energy emitted by laser source 1312 topolygon 1350. The single plane mirror may provide higher resolutions atthe top and bottom portions of the vertical field of view than themiddle portion, whereas the multi-plane mirror may provide higherresolution at a middle portion of the vertical field of view than thetop and bottom portions. Mirror 1360 may be a galvanometer. Varying theoscillation speed within an oscillation cycle can enable scanningsubsystem 1302 to acquire sparse or dense data points within the FOV.For example, if dense data points are required (for a particular ROI),the movement speed may be reduced, and if sparse data points arerequired (for non-ROIs), the movement speed may be increased.

FIG. 13B shows an illustrative block diagram of LiDAR system 1360according to an embodiment. LiDAR system 1360 is essentially the same asLiDAR system 1300, except laser subsystem 1310 has been replaced withlaser subsystem 1370 and fiber tip angles 1345 has been replaced withbeam angles 1385. Laser subsystem 1370 can include laser source 1372 andsplitter 1374. Splitter 1374 is operative to provide several beams, suchas beams 1375-1377, that are derived from lone laser source 1372. Anynumber of beams may exit out of splitter 1374, as indicated the “n”designation of beam 1377. Splitter 1374 is constructed to such that eachof beams 1375-1377 exits splitter 1374 at a precise angle. This ensuresthat the desired angle, a, exists between adjacent beams. That is, theinter-beam angle (e.g., change of angle between adjacent beams) is thesame. The actual inter-beam angle may depend on several factors,including, for example, frame rate, mirror movement and speed, polygonspeed, ROIs, repetition rate, etc. Additional discussion of howsplitters according to embodiments discussed herein are able to controlthe inter-beam angle of all existing beams can be found in FIGS. 19, 20,21A, 21B, 21C, 22A, 22B, 22C, 22D, 22E, 22F, 22G, 23, 24, 25, 26A, 26B,27A, and 27B. Beam angles 1385 may be used as a design constraint withinwhich scanning sub-system 1302 operates in order to optimally performscanning.

FIG. 14 shows illustrative fiber tip arrangement according to anembodiment. Four fiber tips 1401-1404 are shown to be oriented withrespect to each other such that the same angle α exist between adjacentfiber tips. Multiple fiber tips (as opposed to just one fiber tip) maybe used so that high data collection is achieved. When an ROI is beingscanned, the mirror movement speed is adjusted to a ROI speed (e.g., aspeed that is slower than a sparse or non-ROI speed), the combination ofadditional fiber tips and reduced relative mirror movement speed yieldsdenser data capture. Moreover, when a non-ROI is being scanned, themirror movement speed operates at a non-ROI speed (e.g., a speed that isfaster than the ROI speed), the presence of multiple fiber tips ensuresthat sufficient data collection is achieved. The angle α may be selectedbased on properties of the light energy being emitted by each fiber tip(e.g., size), speed and movement characteristics of a mirror (e.g.,mirror 1360) for both ROIs and non-ROIs, and speed of the polygon (e.g.,polygon structure 1350). The angles between each of tips may be the sameor they can be different.

In some embodiments, all four fiber tips may be associated with the samelaser source. Thus, if the laser source is turned OFF, none of the fibertips will emit light energy. In another embodiment, each fiber tip maybe associated with its own respective laser source. This embodimentprovides a high degree of ON/OFF control of each fiber tip. In yetanother embodiment, a subset of the fiber tips may be associated withthe same laser source. For example, fiber tips FT1 and FT3 may share afirst common laser source, and fiber tips FT2 and FT4 may share a secondcommon laser source. This embodiment provides a balance between all ornone and individual ON/OFF control.

FIG. 15A shows a multiple mirror alignment arrangement (MMAA) 1500 thatmay be used for ROI and non-ROI embodiments. MMAA 1500 is an alternativeto using multiple fiber tips such as that shown in FIG. 14 . As shown,MMAA 1500 shows collimator 1510, partial reflective mirrors 1521-1523,and reflective mirror 1524. Light energy originating from a laser source(not shown) is routed to collimator 1510, which directs light energy topartial reflective mirror 1521. Partial reflective mirror 1521 permits aportion of the light energy to pass through (shown as exit path 1531)and the remaining light energy is redirected to partial reflectivemirror 1522. Partial reflective mirror 1522 allows a portion of thelight energy to pass through to partial reflective mirror 1523. Partialreflective mirror 1522 redirects light energy along exit path 1532.Partial reflective mirror allows a portion of the light energy to passthrough to partial reflective mirror 1524. Partial reflective mirror1523 redirects light energy along exit path 1533. Reflective mirror 1524may redirect all or at least a portion of all the remaining light energyalong exit path 1534.

The angles between adjacent exit paths may be selected to achieve thedesired resolution for ROIs and non-ROIs. For example, angles betweenadjacent exit paths may be similar to the α angles shown in FIG. 14 . Insome embodiments, the angle between adjacent exit paths may be fixed. Inother embodiments, the angle between adjacent exit paths may bevariable. Variable angle adjustment may be used to provide differentresolutions on demand. For example, if the LiDAR system is being used ina vehicle, the angles may be set to a first configuration when thevehicle operating in a first mode (e.g., driving at highway speeds orvehicle is driven by a first driver) and may be set to a secondconfiguration when the vehicle is operating in a second mode (e.g.,driving at city speeds or vehicle is driven by a second driver).

FIG. 15B shows another multiple mirror alignment arrangement (MMAA) 1501that may be used for ROI and non-ROI embodiments. MMAA 1501 is analternative to MMAA 1500. As shown, MMAA 1501 shows collimator 1512,partial reflective mirrors 1525-1527, reflective mirror 1528, and exitpaths 1535-1538. MMAA 1501 is similar to MMAA 1500 with exception of thepositioning of collimator 1512. As shown, collimator 1512 is positionedabove mirror 1525. If desired, collimator 1512 can be positioned belowmirror 1528. As a further alternative, collimator 1512 can be aimed at adifferent mirror such as mirror 1526 or mirror 1527, and such mirrorscan redirect the light energy as necessary to achieve the desiredresults.

FIG. 15C shows an illustrative multiple collimator arrangement 1550 thatmay be used for ROI and non-ROI embodiments. Arrangement 1550 caninclude collimators 1561-1563. Each of collimators 1561-1563 may beassociated with its own laser source. Associating each collimator withits own laser source enables selective turning ON and OFF of lightenergy emanating from each collimator. For sparse regions, one or moreof the laser sources may be turned OFF (to save power) and for denseregions, all laser sources may be turned ON to maximize resolution. Eachof collimators 1561-1563 may be fixed in a particular orientation toachieve the desired α angle between each collimator. If desired, each ofcollimators 1561-1563 may be movable to dynamically adjust the α anglebetween each collimator.

FIG. 15D shows an illustrative collimator and lens arrangement 1570 thatmay be used to control divergence of the light beam existing collimator1571 according to an embodiment. Lens 1572 may be moved towards and awayfrom collimator 1571 to adjust divergence of the light beam. Arrangement1570 may be used to adjust the size of the light beam as it is projectedby the scanning system. For ROI regions, it may be desirable to have arelatively narrow beam. To produce a relatively narrow beam, lens 1572may positioned at a narrow beam distance away from the collimator 1571.For non-ROI regions, it may be desirable to have a relatively wide beam.To produce a relatively wide beam, lens 1572 may positioned at a widebeam distance away from the collimator 1571.

FIG. 16 shows illustrative scanning resolution using multiple fibertips, a multiple mirror alignment arrangement, or multiple collimatorarrangement according to an embodiment. The illustrative verticalresolution lines from fiber tips (FT1-FT4) are shown. The resolutionlines are grouped according to sparse resolution and dense resolution asshown. In sparse regions, the scanning system is moving the mirror at arelatively faster speed than when in the dense region, and in denseregions, the scanning system is moving the mirror at a relatively slowerspeed than when in the sparse region. The spacing between the adjacentscanning lines (as shown by the repeated pattern of FT₁-FT₄) issubstantially equidistant. This equidistant spacing may be made possibleby coordinating the alignment of the fiber tips with the frame rate,mirror speed, polygon speed, and any other suitable factors. Incontrast, if alignment of fiber tips is not properly coordinated, theequidistant spacing may not be possible, thereby yielding an undesirablescanning pattern. In the dense region, each fiber tip may providemultiple lines of resolution. For example, as shown, FT1 provides fourlines of resolution before FT2 provides its four lines of resolution.Thus, each fiber tip provides four lines of resolution beforetransitioning to the next fiber tip. It should be understood that thenumber of lines of resolution provided by each fiber tip depends on anumber of factors, including, for example, mirror speed, polygon speed,and angle between fiber tips. The lines of resolution among fiber tipsmay interlace at the transition between the sparse and dense regions.For example, at least one line of resolution from one or more of fibertips FT2-FT4 may be interlaced among the four lines of resolutionpertaining to FT1 (as shown in FIG. 17A).

The angle between the fiber tips (e.g., the α) may be selected based onthe mirror speeds, polygon speed, desired angular resolution of the ROI,and a requirement for the spacing between the resolution lines in thesparse region(s) to be substantially equidistant to each other. At leasttwo different mirror speeds are used to provide the dense and sparseresolutions, and it is the variance in mirror speeds that can cause theresolution lines to be non-equidistant if the angles between fiber tipsare not properly aligned. For example, assume that the angle of thedense region is θ. θ can represent the total degrees within the FOV thatare part of the ROI and require dense resolution. If the mirror speed isconstant throughout the entire frame, the angle between fiber tips, α,can be approximately θ/n, where n is the number of fiber tips. Thisα_(cs), referred to as angle with constant speed may represent a targetangle for the fiber tips, but additional calculations are required totake into account that the mirror operates at different speeds, and as aresult α, cannot be set to exactly θ/n. The sparse regions must be takeninto account. In the sparse region, assume that the desired anglebetween adjacent lines of resolution is ϕ. For the example, ϕ may existbetween FT1 and FT2, between FT2 and FT3, between FT3 and FT4, betweenFT4 and FT1 in the sparse region. In order to achieve ϕ betweendifferent fiber tips, the angle between fiber tips can be calculated bythe following equation:α=α_(vs) =ϕ*n*2−−ϕwhere α_(vs) is the angle with a variable speed mirror, ϕ is the anglebetween adjacent lines of resolution within the sparse region, n is thenumber of fiber tips, and the number 2 is a scaling factor to take intoaccount overlapping lines of resolution. The variables of ϕ, n, mirrorspeed, and polygon speed are selected such that α_(vs) is the same as orapproximately the same as α_(cs). Selecting the variables such thatα_(vs) is the same as or approximately the same as α_(cs), enables thescanning system to achieve the desired scanning densities for both ROIand non-ROI regions within the FOV each frame.

FIG. 17A shows another illustrative diagram of vertical resolution usingmultiple fiber tips or a multiple mirror alignment arrangement,according to an embodiment. Sparse regions and a dense region are shown.Four fiber tips FT1-4 are used. In the sparse region, the resolutionlines for each fiber tip are evenly spaced. In the dense region, thevertical lines of resolution are substantially more dense than thevertical lines of resolution in the sparse regions. Within the denseregion, the vertical lines of resolution are grouped predominantly foreach fiber tip, however, interlacing resolution lines from other fibertips may exist within a particular group.

FIG. 17B shows an illustrative close-up view of a sparse region withinFIG. 17A and FIG. 17C shows an illustrative close-up view of the denseregion within FIG. 17A, according to various embodiments. Note that thescaling factor in FIG. 17B is less zoomed in than it is in FIG. 17C. Asa result, FIG. 17B shows lines of resolution for multiple fiber tips,and where FIG. 17C shows multiple lines of resolution for only one fibertip.

The dynamic resolution discussed above has been in the context ofdynamic vertical resolution. If desired, the laser subsystem (e.g., thefiber tips, multiple mirror alignment arrangement, or multiplecollimator arrangement) can be oriented in a horizontal direction (asopposed to the above-described vertical direction) to provide dynamichorizontal resolution.

Assuming speed changes to mirror movement are used to control thevertical resolution, the repetition rate or time interval can be changedto dynamically control the horizontal resolution. This provides dualaxis dynamic resolution control that can be synchronized by a controller(e.g., ROI controller 1340) to provide increased resolution for ROIs anddecreased resolution for non-ROIs for both vertical and horizontalorientations. For example, when the scan cycle comes across an ROI, themirror movement speed is decreased and the time interval betweensuccessive light pulses is decreased (thereby increasing repetitionrate). When the scan cycle comes across a non-ROI, the mirror movementspeed is increased and the time interval between successive light pulsesis increased (thereby decreasing repetition rate).

In some embodiments, the laser source(s) can be selectively turned ONand OFF to provide vertical dynamic range (assuming the laser subsystemis oriented as such). This can eliminate the need to adjust the mirrorspeed to achieve dynamic vertical resolution. If desired, however, thelaser source(s) can be selectively turned ON and OFF in conjunction withvariations in mirror movement speed.

FIG. 18 shows illustrative FOV 1800 with variable sized laser pulsesaccording to an embodiment. FOV 1800 includes two sparse regions and onedense region as shown. Both the sparse and dense regions showillustrative light pulses that take the form of different sized circles.The sparse sized circles are larger than the dense sized circles. Whenthe scanning system is projecting light to sparse region, the mirrorspeed may be moving at a sparse speed and the repetition rate may be setto a sparse region repetition rate. Conversely, when the scanning systemis projecting light to the dense region, the mirror speed may be movingat the dense speed and the repetition rate may be set to a dense regionrepetition rate. The sparse speed is faster than the dense speed and thesparse region repetition rate is slower than the dense region repetitionrate. As a result, there are fewer light pulses being sent into thesparse region than in the dense region. If the circle size of the lightpulses projected into the sparse region were the same size as thecircles in the dense region, underfilling could exist. Underfill mayoccur when too much space exists between adjacent light pulse circles.Thus, in order to minimize underfill, it is desirable to project anappropriately sized light pulse for both the sparse and dense regions.

The ROI concepts discussed above in connection with FIGS. 13A, 13B, and16-18 can also be realized using single source, multi-beam (SSMB)splitters according to embodiments discussed herein. SSMB splittersaccording to embodiments discussed herein can produce multiple beamsfrom a single source, precisely control the exit angle of each beam, andensure that each beam has substantially the same intensity. In addition,SSMB splitters eliminate beam angle alignment issues that can sometimesplague other beam splitters (e.g., those shown in FIGS. 15A-D).Manufacturability and ease of assembly, and by extension, ease ofestablishing and maintaining precise inter-beam angles is a hallmark andadvantage of the SSMB splitter embodiments discussed herein. The SSMBmay be a monolithic structure with different coatings applied to one ortwo surfaces thereof.

FIG. 19 shows illustrative SSMB splitter 1900 according to anembodiment. SSMB splitter 1900 can receive a single beam from singlebeam source 1910 and produce N beams, where N is any number of beams. Asshown, SSMB splitter 1900 produces four beams, shown as beams 1921-1924.Beams 1921-1924 are transmitted out of SSMB splitter via exit plane 1902at angles, α₁, α₂, α₃, and α₄, respectively, and each of beams 1921-1924have respective intensities i₁-i₄. The inter-beam angle between adjacentbeams is the same. For example, equation 1 below shows that theinter-beam angle (IBA) is same for each adjacent pair of beams.IBA=Δ(|α1−α2|)=Δ(|α2−α3|)=Δ(|α3−α4|)  (1)

In addition the intensities of each beam are also the same, orsubstantially the same, as shown by equation 2, below.i1=i2=i3=i4  (2)

The inter-beam angles are such that each of beams 1921-1924 converges atthe same point at a fixed distance, d, from exit plane 1902.

FIG. 20 shows an illustrative block diagram of SSMB splitter 2000according to an embodiment. SSMB splitter 2000 can include first planarsurface 2010, transmission medium 2011, second planar surface 2012, beaminjection portion 2020, and beam intensity equalizing portion(s) 2030.During use of SSMB splitter 2000, input light beam 2040 can be receivedvia beam injection portion 2020, and input light beam 2040 interactswith first planar surface 2010, transmission medium 2011, second planarsurface 2012, and beam intensity equalizing portion(s) 2030 to produceoutput beams 2051-2054. Only four output beams are shown, but it shouldbe understood that any number of beams (e.g., two or more beams) may beproduced by SSMB splitter 2000. Each of output beams 2051-2054 can havesubstantially the same intensity, i, and the same inter-beam angle,α_(IBA), can exist between adjacent output beams. In addition, outputbeams 2051-2054 converge and exit SMBB splitter 2000 at equidistanceangles. Output beams 2051-2054 can be produced when input light beam2040 is reflected between first and second planar surfaces 2010 and2012, and the reflected light exits out of one or both of first andsecond planar surfaces 2010 and 2012. In some embodiments, an exit beamcan be the reflection of input light beam 2040 at beam injection portion2020.

First planar surface 2010, transmission medium 2011, and second planarsurface 2012 can be arranged with respect to each other to control theexit angle of beams 2051-2054 such that the same inter-beam angle,α_(IBA), exists between adjacent output beams. According to embodimentsdiscussed herein, control over the exit angle (and thus by extension,the inter-beam angle) can be achieved by ensuring that the relativeangles of first and second planar surfaces 2010 and 2012 vary from eachother by a wedge angle. The wedge angle ensures that first and secondplanar surfaces are not parallel to each other. The value of the wedgeangle (or degree to which first and second planar surfaces 2010 and 2012are not parallel to each other) can depend on several factors, includingan angle of incidence (AOI) of input light beam 2040, a diameter ofinput light beam 2040, the desired inter-beam angle, α_(IBA), and adesired inter-beam spacing. The AOI of input light beam 2040 can referto the angle at which light beam 2040 makes with respect to the normalto the surface (e.g., surface of beam injection portion 2020, firstplanar surface 2010, or second planar surface 2012) at the point ofincidence. Inter-beam spacing (IBS) can refer to the spacing betweenadjacent output beams at the exit plane (e.g., first and/or secondplanar surfaces 2010 and 2012).

In some embodiments, arrangement of first planar surface 2010 at a wedgeangle with respect to second planar surface 2012 may be referred to as awedged Fabry-Perot. In a relatively simple embodiment, first planarsurface 2010 and second planar surface 2012 can both be glass platesthat are separated by transmission medium 2011 such as air. In thisembodiment, first planar surface 2010 can be constructed from a materialthat is partially reflective, which enables light to pass through and tobe reflected. Second planar surface 2012 may be constructed from amaterial that is completely reflective, which reflects all lightinterfacing therewith.

In another embodiment, SMBB splitter 2000 can be a monolithic structuresuch as a prism that includes first planar surface 2010, transmissionmedium 2011, second planar surface 2012, beam injection portion 2020,and beam intensity equalizing portion(s) 2030. In some embodiments, theprism can be a trapezoidal prism (e.g., as shown in FIGS. 22A-22B). Inthe monolithic or prism embodiments, first planar surface 2010,transmission medium 2011, and second planar surface 2012 may be includedas a single integrated structure (e.g., a piece of glass). For example,in one such prism embodiment, beam intensity portions 2030 can beapplied to or integrated with first surface 2010 and a mirror coatingcan be applied to or integrated with second planar surface 2012.

Beam intensity equalizing portion(s) 2030 are operative to ensure thatthe intensity of each of output beams 2051-2054 is substantially equal.Beam intensity equalizing portion(s) 2030 may be disposed on one or bothof first and second planar surfaces 2010 and 2012. Portions 2030 may bea dielectric material or a metal material. Portions 2030 can be thinfilm, deposition, or coating. Each of beam equalizing portions 2030 areselected to have the appropriate balance of reflectivity andtransmissivity to ensure the intensity of output beams 2051-2054 aresubstantially equal. Reflectivity is inversely proportional totransmissivity. That is, a 100% reflective material reflects 100% of thelight, and 0% of the light can pass through. A 100% transmittancematerial allows 100% of the light to pass through, but no light isreflected. The balancing of the reflectivity/transmissivity ratios canbe implemented as continuously variable change inreflectivity/transmissivity ratios or step-wise variablereflectivity/transmissivity ratios.

Beam injection portion 2020 can refer to the region in which input lightbeam 2040 initially interfaces with SSMB splitter 2000. In someembodiments, one of the beam equalizing portions 2030 may includeinjection portion 2020. In another embodiment, first planar surface 2010may include injection portion 2020. In yet another embodiment, beaminjection portion 2020 may be a channel designed to transmit lightthrough a barrier that may otherwise completely reflect input beam awayfrom SSMB splitter 2000. As a specific example, the injection site maybe located on a mirror coated reflective surface. In order to pass inputlight beam 2040 into SSMB splitter 2000, beam injection portion 2000 canserve as the conduit for allowing light to pass through the mirrorcoated reflective surface.

SSMB splitter 2000 can be implemented in many different variations thatinclude first planar surface 2010, transmission medium 2011, secondplanar surface 2012, beam injection portion 2020, and beam intensityequalizing portion(s) 2030. A few of these specific variations are nowdiscussed.

In one embodiment, first planar surface 2010 can be constructed from amaterial that is partially reflective, which enables light to passthrough and to be reflected. Second planar surface 2012 may beconstructed from a material that is completely reflective, whichreflects all light interfacing therewith. Transmission medium 2011 maybe constructed from the same material as first planar surface 2010. Beamintensity equalizing portion(s) 2030 may be disposed on first surface2010. Beam injection portion 2020 may be located on the same side asfirst surface 2010. Output beams 2051-2054 may exit out of the same sideas first surface 2010.

FIG. 21A shows illustrative wedge splitter 2100 according to anembodiment. Wedge splitter 2100 can include prism structure 2102, whichincludes first surface 2103, internal portion 2104, and second surface2105. First surface 2103 may have relative angle X+W, and second surface2105 may have relative angle X, where W represents the wedge angle. Beamintensity equalizing portion 2106 may be applied to first surface 2103.Input beam 2107 may be injected into wedge splitter 2100 (at an AOIangle) via portion 2106 through first surface 2103. Output beams 2108can exit out of splitter 2100 via first surface 2103 and portion 2106.In one embodiment, second surface 2105 may be coated with a mirrorsurface to reflect all light back to first surface 2103. In anotherembodiment, second surface 2105 can be partially reflective, to enableoutput beams 2109 to exit out of second side 2015 (as shown).

FIG. 21B shows illustrative wedge splitter 2110 according to anembodiment. Wedge splitter 2110. Wedge splitter 2110 can include prismstructure 2111, which includes integrated first surface and beamintensity equalizing portion 2112, internal portion 2113, and secondportion 2114. Wedge splitter 2110 is similar to wedge splitter 2100 ofFIG. 21A, except that first surface and beam intensity portions areintegrated. Integrated first surface and beam intensity equalizingportion 2112 may have relative angle, X+W. In this particularembodiment, the beam intensity equalizing portion may be responsible forwedge angle, W, of the first surface. Second surface 2114 may include amirror portion (e.g., a mirror coating). Input beam 2117 enters wedgesplitter 2110 and output beams 2118 exit out of portion 2112.

FIG. 21C shows illustrative wedge splitter 2120 according to anembodiment. Wedge splitter 2120 can include mirror portion 2121 (e.g.,which is analogous to a first surface), internal portion 2122, wedgeportion 2123 (e.g., which is analogous to a second surface), andmirror-less portion 2124. Mirror portion 2121 has relative angle, X, andwedge portion has relative angle X+W. Wedge splitter 2120 may have aprism structure. Mirror portion 2121 can be fully reflective, whichprevents light penetration. Thus, mirror-less portion 2124 exists withinmirror portion 2121 to allow input beam 2127 to enter wedge splitter2120. Output beams 2128 exit out of wedge portion 2123. Note that inthis embodiment, the input and output beams enter and exit on oppositesides of wedge splitter 2120.

FIGS. 22A and 22B show respective illustrative side and perspectiveviews of wedge splitter 2200 according to an embodiment. In addition,FIGS. 22A and 22B show illustrative internal reflections of the lightwithin wedge splitter 2200. Wedge splitter 2200 is a trapezoidal prismwith first surface 2210, internal portion 2211, and second surface 2212.Beam equalizing portions 2213-2216 are shown to be disposed on firstsurface 2210 (in FIG. 22A but not in FIG. 22B). First surface 2210 isaligned at relative angle X+W, and second surface 2212 is aligned atrelative angle X. The wedge angle, W, ensures that first and secondsurfaces 2210 and 2212 are not parallel. Input beam 2221 has an AOIangle and is injected into wedge splitter 2200 via equalizing portion2213. A portion of input beam 2221 is reflected as output beam 2233 andanother portion of input bam 2221 is transmitted through internalportion 2211 as internal beam 2223. Internal beam 2223 interacts withsecond surface 2212 and is reflected back towards first surface 2210 asinternal beam 2224. A portion of internal beam 2224 exits wedge 2200 asoutput beam 2234 and a portion of internal beam 2224 is reflected backto second surface 2212 as internal beam 2225. Internal beam 2225interacts with second surface 2212 and is reflected back towards firstsurface 2210 as internal beam 2226. A portion of internal beam 2226exits wedge 2200 as output beam 2235 and a portion of internal beam 2226is reflected back to second surface 2212 as internal beam 2227. Internalbeam 2227 interacts with second surface 2212 and is reflected backtowards first surface 2210 as internal beam 2228. A portion of internalbeam 2228 exits wedge 2200 as output beam 2236.

Beam equalization portions 2213-2216 may be stepped coated into fourseparate bands or zones on surface 2210. Each portion 2213-2216 may be adielectric multilayer. The dielectric may be an oxide layer that isdeposited onto the prism substrate. Each portion 2213-2216 may occupysimilar lengths along front surface 2210 (e.g., on the order ofmillimeters). Each portion 2213-2216 may be separated by theapproximately same sized transition zones (e.g., on the order ofmicrons). Each portion 2213-2216 may have differentreflectivity/transmissivity ratios. For example, in one embodiment,portion 2213 may be 25% reflective, and 75% transmissive; portion 2214may be 66% reflective, and 34% transmissive; portion 2215 may be 50%reflective, and 50% transmissive; and portion 2216 may be greater than99.5% transmissive. It should be understood that that these ratios aremerely illustrative and that any suitable ratios may be used to achievesubstantially uniform beam intensity for all outgoing beams.

The AOI of input beam 2221 may be selected to ensure that output beams2233-2236 converge at the same point at a fixed distance away from firstsurface 2210 (as shown, for example, in FIG. 19 ). For example, the AOIangle of input beam 2221 can range between 15 and 35 degrees, 17 and 32degrees, or 20 and 30 degrees. The wedge angle, W, can be less than onedegree. For example, the wedge angle, W, can range between 0.25 and 0.75degrees, or 0.34 and 0.70 degrees.

FIGS. 22C and 22D show illustrative perspective and side views of wedgesplitter 2240 according to an embodiment. FIGS. 22C and 22D showillustrative internal reflections of the light within wedge splitter2240 and output beams. Wedge splitter 2240 can be a trapezoidal prismwith first surface 2241 and second surface 2242. Beam equalizing layers2243-2246 are shown to be disposed on first surface 2241. The relativeangles of first and second surfaces 2241 and 2242 may vary, for example,by a wedge angle of 0.35 degrees. Note that the prism has a thicknesswidth, W₁. It should be understood that the thickness width may vary.Beam equalizing layers 2243-2246 may each occupy an equal amount of areaon first surface 2241. Each of layers 2243-2246 may be separated by gaps(as shown). In some embodiments, layers 2243-2246 can cover the entirethickness width, or portion thereof, of first surface 2241.

FIGS. 22E and 22F show illustrative perspective views of wedge splitter2250 according to an embodiment. FIGS. 22E and 22F show illustrativeinternal reflections of the light within wedge splitter 2250 and outputbeams. Wedge splitter 2250 can be a trapezoidal prism with first surface2251 and second surface 2252. Beam equalizing layers 2253-2256 are shownto be disposed on first surface 2251. The relative angles of first andsecond surfaces 2251 and 2252 may vary, for example, by a wedge angle of0.7 degrees. Wedge splitter 2250 with a larger thickness width, W₂,which may be larger than the thickness width of wedge splitter 2240.

FIG. 22G shows another illustrative perspective views of wedge splitter2250 according to an embodiment, but shows the input, reflected, andoutput light as a beam (as opposed to a single ray).

FIG. 23 shows illustrative wedge splitter 2300 according to anembodiment. Wedge splitter 2300 is a trapezoidal prism that is similarto wedge splitter 2200, except it includes a chamfer edge 2350 and hasfive output beams. The input beam, internal reflection beams, and outputbeams are all illustrated.

FIG. 24 shows illustrative wedge splitter 2400 according to anembodiment. Wedge splitter 2400 is a trapezoidal prism that is similarto wedge splitter 2200, except the input and output beams are onopposite sides and there are only three output beams. The input beam,internal reflection beams, and output beams are all illustrated.

FIG. 25 shows illustrative wedge splitter 2500 according to anembodiment. Wedge splitter 2300 is a trapezoidal prism with acontinuously variable equalization portion 2330. In this embodiment,equalization portion 2330 is deposited as a continuously variable mediumthat changes in thickness as a position along the surface of wedgesplitter 2500. This is in contrast to the step-wise application ofdifferent thicknesses of the equalization portion as discussed above.The input beam, internal reflection beams, and output beams are allillustrated.

FIG. 26A shows illustrative SSMB splitter 2600 according to anembodiment. SSMB splitter 2600 uses a different approach than thosediscussed above in connection with FIGS. 21A, 21B, 21C, 22A, 22B, 22C,22D, 22E, 22F, 22G, 23, 24, and 25 to generate multiple converging andsubstantially equal intensity output beams from a single beam source.SSMB splitter 2600 uses stacked splitter array 2610 in combination withfaceted deflector 2630 to convert single input beam 2640 into multipleoutput beams 2651-2654. Laser source 2641 may emit a laser beam towardlens 2642, which can collimate the laser beam from laser source 2641 tostacked splitter array 2610. Stacked splitter array 2610 can includeseveral prism structures 2651-2654 that are substantially perfectlyaligned with each other such that each of interstitial beams 2121-2125exit stacked splitter array 2610 at the same angle. For example, asshown, interstitial beams 2121-2125 exit stacked splitter array 2610 at90 degrees. Arranging each of prism structures 2651-2654 to be stackedin the same orientation as each other is much easier to assemble thanattempting to align the prism structures at different angles withrespect to each other. Using this approach, faceted deflector 2630 isresponsible for controlling the exit angle of output beams 2651-2654.Faceted deflector 2630 (also shown in close up in FIG. 26B) can includemultiple facets 2631-2634. Facets 2631-2634 can control the exit angleof output beams 2651-2654 by redirecting interstitial beams 2621-2624 tothe desired angle. Facet deflector 2630 may ensure that the inter-beamangle is the same for beams 2651-2654. In addition, facet deflector 2630may ensure that beams 2651-2654 converge at the same point at a fixeddistance away from SSMB splitter 2600.

Prism structures 2611-2614 may be coated with differentreflectivity/transmissivity ratios to ensure that the intensity ofoutput beams. Faceted deflector 2630 may be single piece construction ora multi-piece construction. Faceted deflector 2630 may be molded ormachined or an assembly of four wedge splitters according to embodimentsdiscussed herein.

FIG. 27A shows illustrative SSMB splitter 2700 according to anembodiment. SSMB splitter 2700 is similar to SSMB 2600, but addsdivergence lens 2743 in the beam path between lens 2742 and stackedsplitter array 2710. Divergence lens 2743 can be added to compensate forthe convergence imposed on output beams 2751-2754 by faceted deflector2730. That is, in some embodiments, a desired level of focus may berequired at the focal length of SSMB splitter 2700. In some embodimentsthat do not use divergence lens 2743, output beams 2751-2754 may be morefocused than desired. Hence, the addition of divergence lens 2743 can“pre” diverge interstitial beams 2721-2724 prior to be converged byfaceted deflector 2730 so that the desired focus is achieved at thefocal length. FIG. 27B shows a close up of faceted deflector 2730.Deflector 2730 can be a planoconvex (PCX) lens. This particular PCX lenscan include a relatively smooth surface.

It is believed that the disclosure set forth herein encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Eachexample defines an embodiment disclosed in the foregoing disclosure, butany one example does not necessarily encompass all features orcombinations that may be eventually claimed. Where the descriptionrecites “a” or “a first” element or the equivalent thereof, suchdescription includes one or more such elements, neither requiring norexcluding two or more such elements. Further, ordinal indicators, suchas first, second or third, for identified elements are used todistinguish between the elements, and do not indicate a required orlimited number of such elements, and do not indicate a particularposition or order of such elements unless otherwise specifically stated.

Moreover, any processes described with respect to all of the FIGS. aswell as any other aspects of the invention, may each be implemented bysoftware, but may also be implemented in hardware, firmware, or anycombination of software, hardware, and firmware. They each may also beembodied as machine- or computer-readable code recorded on a machine- orcomputer-readable medium. The computer-readable medium may be any datastorage device that can store data or instructions which can thereafterbe read by a computer system. Examples of the computer-readable mediummay include, but are not limited to, read-only memory, random-accessmemory, flash memory, CD-ROMs, DVDs, magnetic tape, and optical datastorage devices. The computer-readable medium can also be distributedover network-coupled computer systems so that the computer readable codeis stored and executed in a distributed fashion. For example, thecomputer-readable medium may be communicated from one electronicsubsystem or device to another electronic subsystem or device using anysuitable communications protocol. The computer-readable medium mayembody computer-readable code, instructions, data structures, programmodules, or other data in a modulated data signal, such as a carrierwave or other transport mechanism, and may include any informationdelivery media. A modulated data signal may be a signal that has one ormore of its characteristics set or changed in such a manner as to encodeinformation in the signal.

It is to be understood that any or each module or state machinediscussed herein may be provided as a software construct, firmwareconstruct, one or more hardware components, or a combination thereof.For example, any one or more of the state machines or modules may bedescribed in the general context of computer-executable instructions,such as program modules, that may be executed by one or more computersor other devices. Generally, a program module may include one or moreroutines, programs, objects, components, and/or data structures that mayperform one or more particular tasks or that may implement one or moreparticular abstract data types. It is also to be understood that thenumber, configuration, functionality, and interconnection of the modulesor state machines are merely illustrative, and that the number,configuration, functionality, and interconnection of existing modulesmay be modified or omitted, additional modules may be added, and theinterconnection of certain modules may be altered.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that theparticular embodiments shown and described by way of illustration are inno way intended to be considered limiting. Therefore, reference to thedetails of the preferred embodiments is not intended to limit theirscope.

What is claimed is:
 1. An optical splitter for use with a lightdetection and ranging (LiDAR) system, comprising: a first portion of theoptical splitter, wherein the first portion of the optical splitterincludes a region in which an input light beam interacts with theoptical splitter at an angle of incidence (AOI); a first planar surface;and a second planar surface that is unparallel to the first planarsurface, the first planer surface and the second planar surface forminga wedge angle; and one or more beam intensity equalizing portionsdisposed on one of the first planar surface or the second planarsurface, wherein the optical splitter emits a plurality of output beamsthat are derived from the input light beam via the first planar surface,the second planar surface, and the one or more beam intensity equalizingportions, wherein the wedge angle is configured such that each of theplurality of output beams is directed at a respective output angle andwherein one or more optical characteristics of the one or more beamintensity equalizing portions are configured such that at least two ofthe plurality of output beams have substantially similar beamintensities.
 2. The optical splitter of claim 1, wherein the wedge angleformed between the first planer surface and the second planar surface isconfigured based on one or more of the AOI, a diameter of the inputlight beam, an inter-beam angle requirement, and an inter-beam spacingrequirement.
 3. The optical splitter of claim 1, further comprisingoptics configured to control divergence of the plurality output beams.4. The optical splitter of claim 1, wherein the first planar surface andthe second planar surface are surfaces of an optical prism structure. 5.The optical splitter of claim 4, wherein the optical prism structure isa trapezoidal prism.
 6. The optical splitter of claim 1, wherein thewedge angle is configured such that inter-beam angles of adjacent outputbeams of the plurality of output beams are the same.
 7. The opticalsplitter of claim 1, where the first portion of the optical splitter andthe one or more beam intensity equalizing portions are disposed on thefirst planar surface.
 8. The optical splitter of claim 1, wherein thesecond planar surface comprises a completely reflective material.
 9. Theoptical splitter of claim 1, wherein at least some of the one or morebeam intensity equalizing portions comprise a partially reflectivematerial.
 10. The optical splitter of claim 1, wherein the one or morebeam intensity equalizing portions comprise plurality of beam intensityequalizing portions having different reflectivity and transmissivityratios.
 11. The optical splitter of claim 1, further comprising achamfer edge.
 12. The optical splitter of claim 1, wherein the one ormore beam intensity equalizing portions comprise a continuously variablemedium that changes in thickness as a position along one of the firstplanar surface or the second planar surface.
 13. The optical splitter ofclaim 1, wherein the first portion of the optical is disposed on thefirst planar surface and wherein the one or more beam intensityequalizing portions are disposed on the second planar surface.
 14. Alight detection and ranging (LiDAR) system, comprising: an opticalscanner comprising on or more optics; and a laser subsystem comprising alaser source and an optical splitter that produces a plurality of outputbeams that are steered by the optical scanner in accordance with a fieldof view (FOV), wherein the optical splitter comprises: a first portionof the optical splitter, wherein the first portion of the opticalsplitter includes a region in which an input light beam intreacts withthe optical splitter at an angle of incidence (AOI); a first planarsurface; and a second planar surface that is unparallel to the firstplanar surface, the first planer surface and the second planar surfaceforming a wedge angle; and one or more beam intensity equalizingportions disposed on one of the first planar surface or the secondplanar surface, wherein the optical splitter emits a plurality of outputbeams that are derived from the input light beam via the first planarsurface, the second planar surface, and the one or more beam intensityequalizing portions, wherein the wedge angle is configured such thateach of the plurality of output beams is directed at a respective outputangle and wherein one or more optical characteristics of the one or morebeam intensity equalizing portions are configured such that at least twoof the plurality of output beams have substantially similar beamintensities.
 15. The LiDAR system of claim 14, wherein the opticalscanner comprises: a polygon structure; and a mirror optically coupledto the polygon structure.
 16. The LiDAR system of claim 15, wherein themirror is configured to receive the plurality of output beams and directthe output beams to the polygon structure.
 17. The LiDAR system of claim14, wherein the optical splitter comprises a prism structure.
 18. TheLiDAR system of claim 14, further comprising optics configured tocontrol divergence of one or more of the plurality output beams.
 19. TheLiDAR system of claim 14, wherein the one or more beam intensityequalizing portions comprise plurality of beam intensity equalizingportions having different reflectivity and transmissivity ratios.